Grease compositions



United States Patent 3,349,034 GREASE COMPOSITIONS Richard A. Butcoskand William F. Olszewski, Cherry Hill, N.J., assignors to Mobil OilCorporation, a corporation of New York No Drawing. Filed May 5, 1965,Ser. No. 453,517 7 Claims. (Cl. 252-28) ABSTRACT OF THE DISCLOSUREGrease compositions are provided comprising a major proportion of an oilof lubricating viscosity, a minor proportion of a thickening agent andfrom about 0.5 to about percent, by weight, based upon the grease, of athiobis- (dichlorophenol) as an extreme pressure and antiwear agent.

This invention has to do with grease compositions. More specifically,the invention relates to grease compositions having excellent extremepressure and wear properties. There has been a demand for some years forgrease compositions capable of providing satisfactory lubrication whensubjected to rigorous operating conditions. Many grease lubricationoperations are conducted at extreme pressures suchthat greases fail toperform as desired. The compositions become unstable with separation ofthe lubricating oil vehicle and thickening agent of which they arecomprised. As a result, metal parts are inadequately lubricated by thecompositions and become worn or otherwise damaged.

Numerous efforts have been made to improve the extremepressureproperties of grease compositions. Invariably, however, thecompositions are worsened in one or more other properties. For example,sulfurand chlorinecontaining additives used to date have been found tocause softening or loss of shear stability of the compositions. Whilewith some steel mill lubricant greases, such disadvantages can betolerated, no such disadvantages can be tolerated with greases used inball bearings. The same additives and others hitherto used increase theviscosity of the grease compositions, an undesirable characteristic forlow temperature lubrication.

Not only should an additive impart extreme pressure and antiwearcharacteristics to grease compositions, but it should also be fluid orsoluble in the lubricant vehicle of the compositions, or it should bemicrocrystalline in nature in order to avoid surface scratching ofbearing race ways and plugging of small openings in bearing retainersand centralized lubricant pumping systems.

It has now been found that extreme pressure and antiwear properties canbe imparted to grease compositions by incorporating therein a relativelysmall amount of a thiobis(dichlorophenol).

' It is an object of this invention, therefore, to provide greasecompositions having improved extreme pressure and antiwear properties.Another object is to provide such greases without worsening otherdesirable characteristics of grease compositions. A specific object isto provide such grease compositions in which the thickening agent is aninorganic thickener. Other objects of the invention will be apparentfrom the following description.

In accordance with the invention, there are provided grease compositionscomprising a major proportion of an oil of lubricating viscosity, aminor proportion of a thickening agent and from about 0.2 to about 5percent by weight (based upon the grease composition), of a thiobis-(dichlorophenol). Preferred of such phenols is 2,2'-thio- 3,349,d34Patented Got. 24, 1967 2 bis (4,6-dichlorophenol), which is representedby the formula (|)H on 5 c1 O s-Oo I I 01 c1 A wide variety ofthickening agents can be used in the greases of this invention. Includedamong the thickening agents are alkali and alkaline earth metal soaps offatty acids and fatty materials having from about 12 to about carbonatoms per molecule. The metals are typified by sodium, lithium, calciumand barium. Fatty materials are illustrated by stearicacidQhydroxystearic acid, stearin, cottonseed oil acids, oleic acid,palmitic acid, myristic acid; and hydrogenated fishoils. 7

Other thickening agents include salt and salt-soap complexes as: calciumstearate-acetate (Patent No. 2,197,- 263);"barium 'stearate-acetate(Patent No. 2,564,561); calciumstearate-caprylate-acetate complexes(Patent No. 2,999,065); calcium caprylate-acetate (Patent No. 2,999,-066); and calcium salts and soaps of low-, intermediateandhigh-molecular Weight acids and of nut oil acids. Another group ofthickening agents comprises 'su-bstituted ureas, phthalocyanines,indanthrene, pigments such as perylimides (Patent No. 3,137,653),anthanthrones, naphthalic imidazoles and oxazoles.

The preferred thickening or gelling agents employed in the new greasecompositions are essentially, hydrophobic clays. Such thickening agentscan be prepared from clays which are initially hydrophilic in character,but

which have been converted into a hydrophobic condition by theintroduction of long chain hydrocarbon radicals into the surface of theclay particles, prior to their use as a component of a greasecomposition, as, for example, by being subjected to a preliminarytreatment with an organic cationic surface active agent, such as anonium compound. Typical of the latter are dimethyl dibenzyl quaternaryammonium chloride and dimethyl dioctadecyl quaternary ammonium chloride.This method of conversion, being Well known to those skilled in the art,is believed to require no further discussion, and does not form a partof the present invention. More specifically, the clays which are usefulas starting materials in forming the thickening agents to be employed inthe grease compositions, can comprise the naturally occurring chemicallyunmodified clays. These clays are crystalline complex silicates, theexact composition of which is not subject to precise description, sincethey vary widely from one natural source to another. These clays can bedescribed as complex inorganic silicates such as aluminum silicates,

magnesium silicates, barium silicates, and the like, containing, inaddition to the silicate lattice, varying amounts of cation-exchangeablegroups generally regarded as metallic oxide radicals. Hydrophilic clayswhich are particularly useful for conversion to desired thickeningagents include montmorillonite clays, such as bentonite, attapulgite,hectorite, illite, saponite, sepiolite, biotite, vermic ulite, zeoliteclays, and the like. The thickening agent is employed in an amount fromabout 0.5 to about 30, and preferably from 5 percent to 15, percent byweight of the total grease composition.

The lubricating vehicles employed in the grease compositions cancomprise any of the conventional oils of lubricating viscosity includingmineral or synthetic lubricating oils, aliphatic phosphates, esters anddiesters, silicates, siloxanes and oxyalkyl ethers and esters. Minerallubricating oils can be of any suitable lubricating viscosity rangingfrom about 45 SUS at 100 F., to about 3500 SUS at 100 F. and preferablyfrom about 50 to about 250 SUS at 210 F. The oils may have viscosityindexes, varying from below to about 130 or higher. Other hydrocarbonoils include synthetic hydrocarbon polymers having improved viscosityindices, which polymers are prepared by polymerizing an olefin, ormixtures of olefins, having from to 18 carbon atoms per molecule in thepresence of an aliphatic halide and a Ziegler-type catalyst. Suchsynthetic hydrocarbon oils are described by Armstrong et al. inapplication U.S. Ser. No. 314,575, filed Sept. 26, 1963, and nowabandoned.

Synthetic vehicles suitable herein include: polypropylene,poly-propylene glycol, trimethylol propane esters, neopentyl andpentaerythritol esters, di-(2-ethylhexyl) sebacate, di-(Z-ethylhexyl)adipate and related adipates, di butyl phthalate, polyethylene glycoldi-(2-ethyl hexo-ate), and polysiloxanes (silicones).

Outstanding in conjunction with the inorganic clay-type thickenersidentified above are synthetic ester lubricants, particularly esters ofadipic acid and isooctyl and isodecyl alcohols.

When inorganic clay-type thickeners are used, it is generallyadvantageous to include a stabilizing agent such as entaerythritol oranhydroenneaheptitol.

Other improving agents can also be included in the grease compositionsof this invention, in order to obtain the benefit of their knowncharacterizing features. Antioxidants can be used such as amines andmixtures of amines, such as a mixture of dioctyl phenyl amine and4,4'-methylenebis(2,6-dietertiarybutylphenol). Phenyl alphanaphthylamine (PAN) is preferred. Lubricity improving agents such asfree fat, free fatty acids, sulfurized fats, lead soaps and esters ofalkyl and/or aryl acids can be used. Rust inhibitors such as sodiumnitrite are also suitable in the new compositions.

The greases of this invention can be prepared in accordance withconventional grease manufacturing procedures. The extreme pressure andantiwear agent-21 thiobis (dichlorophenol)-can be incorporated in a basegrease when the latter is heated at a temperature about 100 F. to about300 F., and thoroughly mixing of the resulting grease composition. Ifthe grease composition is subjected .to homogenization, as in aManton-G-aulin homogenizer, the agent can be incorporated before orafter homogenization.

The concentration of the extreme pressure and antiwear agent is fromabout 0.2 to about 5, and preferably 0.5 to 2, percent by weight of thefinished grease.

The greases of this invention are illustrated in the several followingexamples. A base grease was prepared from approximately 9 parts byweight of sodium montmorillonite clay treated with dimethyl dibenzyl.quaternary ammonium chloride (identified hereinafter as Clay 1), about 1part by weight of pentaerythritol and about 90 parts by weight of amixture of synthetic neutral esters comprising a mixture of isooctyl andisodecyl adipates (Ester 1 hereinafter). The mixed esters have aviscosity of 62 SUS at 100 F. and 36 SUS at 210 F. The severalcomponents are mixed and heated together in a grease kettle to atemperature of about 300 F. during a time interval of approximately 1-3hours. The resulting mixture is then cooled to about 200 F., and anextreme pressure, antiwear agent-2,2'-thiobis(4,6-dichlorophenol)isincorporated. The material is then homogenized in a Manton- Gaulinhomogenizer at about 2000-3000 pounds per square inch (psi) Theillustrative greases were evaluated on the 4-bal1 extreme pressuretester according to US. Federal Method 6503.1, which provides an indexof load-carrying ability. This shows the maximum load which can beimposed directly upon the grease. From the data measured in this testmean Hertz load values are determined. 'An extreme pressure lubricant isconsidered to be one having a mean Hertz load value above about 30.

4 Example 1 Parts by wt. Clayl 9 Pentaerythritol 1 5 Ester 1 89 PAN lExample 2 Parts by wt. Clay 1 l0 Pentaerythritol 1.67 Mineral oil 88.33

Viscosity at:

210 F., 44.94 SUS. 100 F., 149.3 SUS. 40 F., 7226 centistokes.

The grease composition formed of the three components- 5 identifiedabove has a mean Hertz load value of 28.

When 99 parts by weight of this composition and 1 part by weight of thethiobis compound of Example 1 are mixed together, the grease productobtained thereby has a mean Hertz load value of 36. This is animprovement of approximately 30 percent.

Example 3 Parts by wt. Clay 1 10 Pentaerythritol 1 Sodium nitrite 1.5PAN 1.0 Ester 1 85.5

A grease formed from the foregoing components has a mean Hertz loadvalue of 28.

Addition of 0.5 part by weight of the thiobis compound of Example 1 to99.5 parts by weight of the base grease, increased the mean Hertz loadvalue to 35.

Properties characterizing the final grease composition of Example 3 aregiven below:

ASTM penetration (D217-T),

unworked/worked 288/288. ASTM bomb at 210 F. (D942- 50) 21b. drop/100hours. 50 4-ba11 mean Hertz load (Federal 6503.1) 35 or greater.

Bearing performance at 250 F.,

10,000 r.p.m. (Federal 331) 1000 hours.

grease formed of the foregoing components.

When 1 part by weight of the thiobis compound of Example 1 wasincorporated with 99 parts by weight of the base grease, the mean Hertzload was only increased to 27.9. However, a concentration of 2 percentby weight of the additive, increased the load value to 30.6 therebybringing the grease into the range of extreme pressure lubricants.

Example 5 Parts by wt. Calcium tallow soap 11 Mineral oil, 750 SUS at100 F. 89

The mean Hertz load value was only 21.8 for the grease formed from theforegoing components.

Here again, incorporation of one percent of the thiobis compound ofExample 1 increased the load value to an unsatisfactory value of 27.9. A2.5 percent concentration increased the load value to 34.2.

Example 6 Parts by wt. Lime flour 6.2 Acetic acid 7.1 C14 18 acids 7.5PAN 1 Mineral oil, 400 SUS at 100 F. 78

acids l6 PAN 0.5 Mineral oil, 150 SUS at 100 F. 83.5

A grease formed of the named components has a mean Hertz load of 22.3.One percent concentration of the thiobis compound of Example 1 increasedthe load value slightly to 24.2; however, a value of 35.2 was obtainedwith a 2 percent concentration of the same additive.

Example 8 Parts by wt. Cab-O-Sil Mineral oil, 80 SUS at 100 F. 82

Cab-O-Sil is a silica aerogel having a particle size of about 0.015micron; it is marketed by the Cabot Corporation.

A grease formed of Cab-O-Sil and the mineral oil has a mean Hertz loadof 20.4. One percent of the thiobis compound increased the load value to29.4. In view of this substantial increase with a one percentconcentration of the additive, larger concentrations would furtherincrease the load value to well over 30.

Example 9 Parts by Wt. p-Methoxyphenyl perylimid 18 Silicone fluid, 400SUS at 100 F. 82

A grease formed of the foregoing components following the procedure ofUS. Patent No. 3,108,962, has a mean Hertz load value of 20.1. While aone percent concentration of the thiobis compound of Example 1 increasedthe load value only to 23.7, a five percent concentration provided avalue of 38.7.

The silicone fluid is comprised of phenylmethyl siloxanes having a ratioof approximately 20 methyl groups to one phenyl group, and contains asmall amount of iron octoate.

The greases of this invention are suitable for a wide range ofindustrial applications. Some, for example, are suitable for use asmulti-purpose automotive and aviation greases, serving as chassis,wheel-bearing, grease lubricants. Others are multi-purpose industrialgreases serving as plain-bearing and anti-friction greases for heavilyloaded equipment.

We claim:

1. A grease comprising a major proportion of an oil of lubricatingviscosity,

a grease forming amount of a thickening agent, and

from about 0.2 to about 5 percent by weight, based upon the grease, of athiobis(dichlorophenol).

2. A grease defined by claim 1 wherein the phenol is2,2-thiobis(4,6-dichlorophenol).

3. A grease defined by claim 1 wherein the oil is a synthetic ester.

4. A grease defined by claim 1 wherein the oil is a mineral oil.

5. A grease defined by claim 1 wherein the oil is a synthetichydrocarbon polymer having a viscosity index of at least about andprepared from an olefin having from about 5 to about 18 carbon atoms permolecule.

6. A grease defined by claim 1 wherein the thickening agent is anessentially hydrophobic clay.

7. A grease defined by claim 1 wherein the thickening agent is areaction product of sodium montmorillonite clay and a dimethyl dibenzylquaternary ammonium halide.

References Cited UNITED STATES PATENTS 2,246,314 6/1941 Mikeska 25248.42,554,222 5/1951 Stross 252-28 2,846,392 8/1958 Morway et al 252363,108,962 10/1963 Buehler et a1. 252-51.5

FOREIGN PATENTS 967,826 8/1964 Great Britain.

DANIEL E. WYMAN, Primary Examiner. I. VAUGHN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No,3,349,034 October 24, 1967 Richard A. Butcosk et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, Iines 3 to 10, for that portion of the formula reading C" read----Cl column 3, line 31 for "dietertiarybutylphenol readditertiarybutylphenol Signed and sealed this 17th day of December 1968.

SEAL) LtteSt:

\dward M. Fletcher, Jr. EDWARD J. BRENNER tttesting Officer Commissionerof Patents

1. A GREASE COMPRISING A MAJOR PROPORTION OF AN OIL OF LUBRICATINGVISCOSITY, A GREASE FORMING AMOUNT OF A THICKENING AGENT, AND FROM ABOUT0.2 TO ABOUT 5 PERCENT BY WEIGHT, BASED UPON THE GREASE, OF ATHIOBIS(DICHLOROPHENOL).
 6. A GREASE DEFINED BY CLAIM 1 WHEREIN THETHICKENING AGENT IS AN ESSENTIALLY HYDROPHOBIC CLAY.